1. Field of the Invention
The present invention relates to a transceiver. More particularly, the present invention relates to a transceiver including an antenna apparatus which can be compactly accommodated in a body of the transceiver.
2. Description of the Related Art
A bar whip antenna is used in a portable transceiver. At a time of transmission or reception, the whip antenna is pulled out from a body of the portable transceiver. At a time of wait, the whip antenna is accommodated in the body of the portable transceiver. Electromagnetic waves are received by the whip antenna and processed by a signal processing circuit in the portable transceiver. Also, electromagnetic waves generated by the signal processing circuit are transmitted through the whip antenna.
It is necessary that an impedance of the antenna apparatus of the portable transceiver and an impedance of the signal processing circuit match with each other. Therefore, an impedance matching circuit is used for converting the impedance of the signal processing circuit. However, the impedance of the bar whip antenna when it is accommodated is different from that when it is pulled out. For this reason, if the impedance of the whip antenna is matched with the impedance of the impedance matching circuit with each other in the condition that the whip antenna is pulled out from the body, it is impossible to match the impedance of the whip antenna and the impedance of the impedance matching circuit with each other in the condition that the whip antenna is accommodated.
For this reason, an antenna apparatus is used in which a helical antenna is mounted at an end of a straight (bar) antenna. A portable transceiver containing such an antenna apparatus is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 8-84017). The conventional portable transceiver includes a body 101 and a bar antenna 102 as shown in FIGS. 1 and 2. An end of the bar antenna 102 is inserted into the body 101. The bar antenna 102 includes a bar conductor 103, as shown in FIG. 3. The bar conductor 103 is covered with a dielectric sleeve 104. A conductive terminal 105 is connected to an end inserted into the body 101. The conductive terminal 105 is coupled to the conductor 103.
A dielectric 106 is coupled to the other end of the bar antenna 102, as shown in FIGS. 1 and 2. An conductive connector 107 is coupled to the dielectric 106. A helical antenna 108 is coupled to the conductive connector 107. The helical antenna 108 is covered with a cover 109.
On the other hand, a slide terminal 110 is coupled to the body 101. The slide terminal 110 is slid and connected to the bar antenna 102. The slide terminal 110 is connected to the impedance matching circuit 111. The impedance matching circuit 111 is connected to the signal processing circuit 112. The impedance matching circuit 111 matches the impedance of the bar antenna 102 and the helical antenna 108 with that of the signal processing circuit 112. The signal processing circuit 112 processes electromagnetic waves received by the bar antenna 102 or the helical antenna 108. Moreover, the signal processing circuit 112 generates electromagnetic waves, and transmits the electromagnetic waves through the bar antenna 102 or the helical antenna 108.
The bar antenna 102 is used in an extended state in a case of long distance communication, as shown in FIG. 1. In the condition when the bar antenna 102 is extended, the conductive terminal 105 is connected to the slide terminal 110. The bar antenna 102 transmits or receives the electric wave. The bar antenna 102 is used in the accommodated state in a case of short distance communication, as shown in FIG. 2. In the condition that the bar antenna 102 is accommodated, the conductive connector 107 is connected to the slide terminal 110. The helical antenna 108 transmits or receives electromagnetic waves. The conventional portable transceiver receives electromagnetic waves the impedance being matched, in any case of the accommodated antenna and the extended antenna.
In order to increase a gain, it is necessary that an effective height of the helical antenna 108 is equal to or greater than one fourth of a wave length of electromagnetic waves received by the helical antenna 108. Thus, a number of loops of the helical antenna 108 are required such that the effective height becomes equal to or greater than about one fourth of the wave length of the electromagnetic waves. The helical antenna 108 is needed to have a considerable size in accordance with the number of the loops.
Other portable transceivers are disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 7-131220, JP-A-Heisei 7-122917 and JP-A-Heisei 7-336122) and Japanese Patent Gazette (JP-B-2503856).
A portable transceiver is desirable in which an antenna is compact and a gain characteristic of the antenna is excellent when it is accommodated in a body.
Therefore, an object of the present invention is to provide a portable transceiver in which an antenna is compact and a gain characteristic of the antenna is excellent when it is accommodated in a body.
In order to achieve an aspect of the present invention, a transceiver includes a body, a first antenna fixed to the body, a bar antenna, an insulating section coupled to the bar antenna and a second antenna coupled to the insulating section. The bar antenna can be accommodated in the body. The first and second antennas are electrically connected to form a third antenna when the bar antenna is accommodated in the body.
Desirably, the third antenna has an effective height larger than one fourth of a wave length of a electromagnetic wave receive d by the third antenna.
The bar antenna may be. electrically connected to the first antenna to form a fourth antenna when the bar antenna is pulled out of the body. In this case, the third and fourth antennas have substantially same impedance.
The bar antenna and the second antenna may have substantially same impedance.
Desirably, the fourth antenna have an effective height larger than one fourth of a wave length of electromagnetic waves received by the fourth antenna.
The first and second antennas may be capacitively connected to form the third antenna when the bar antenna is accommodated in the body
In this case, the second antenna may include a conductive portion. And the first antenna and the conductive portion may form a capacitance when the bar antenna is accommodated in the body.
The first antenna and the bar antenna may be capacitively connected to form a fourth antenna when the bar antenna is pulled out of the body.
In this case, the bar antenna may include a second conductive portion. And the first antenna and the second conductive portion may form a capacitance when the bar antenna is pulled out of the body.
The transceiver may further include a first conductive terminal coupled to the first antenna and a second conductive terminal coupled to the second antenna. In this case, the first conductive terminal has a first contacting surface. The second conductive terminal has a second contacting surface. The first conductive terminal contacts the second conductive terminal on the first and second contacting surfaces when the bar antenna is accommodated in the body.
The transceiver may further include a third conductive terminal coupled to the first antenna and a fourth conductive terminal coupled to the bar antenna. The third conductive terminal has a third contacting surface. The fourth conductive terminal has a fourth contacting surface. The third conductive terminal contacts the fourth conductive terminal on the third and fourth contacting surfaces when the bar antenna is pulled out of the body
The first antenna may include a helical antenna.
The second antenna may include a second helical antenna.
In order to achieve another aspect of the present invention, a radio receiver includes a body, a first antenna fixed to the body, a bar antenna, an insulating section coupled to the bar antenna and a second antenna coupled to the insulating section. The bar antenna can be accommodated in the body. The first and second antennas are electrically connected to form a third antenna when the bar antenna is accommodated in the body.
In order to achieve still another aspect of the present invention, a radio transmitter includes a body, a first antenna fixed to the body, a bar antenna, an insulating section coupled to the bar antenna and a second antenna coupled to the insulating section. The bar antenna can be accommodated in the body. The first and second antennas are electrically connected to form a third antenna when the bar antenna is accommodated in the body.
In order to achieve yet still another aspect of the present invention, a method of using a portable terminal includes pushing a bar antenna section into a portable terminal such that the bar antenna section is accommodated in a body of the portable terminal, a first antenna section protruding from the body and the first antenna section and a second antenna section in the body forming a first antenna and pulling out the bar antenna section from the body in transmission such that the bar antenna section and the second antenna section form a second antenna.
The method may further include receiving an electromagnetic wave in a state in which the bar antenna section is pushed into the portable terminal.
The first and second antennas desirably have substantially same impedance.